BMW short-circuit reset by phone (FEM, REM, BDC)
When a BMW body module sees a short circuit on a lamp output, it switches that output off and keeps it off — clearing the fault codes does not bring the light back. DiagBimmer reads the lamp outputs of the FEM / REM or BDC module, shows which ones are switched off and resets them from your iPhone or Android phone. Reading the status is free; the reset is part of the one-time premium purchase.
Get the app
Free to download; premium features unlock with a one-time in-app purchase.
The fault this fixes
A headlight, tail light, brake light or indicator stays dead even with a new bulb, and the fault memory holds a code such as 8041A5 (“Light outputs: Number of permitted short circuit cycles exceeded”) or 804875 (“One or several outputs have exceeded the approved number of short-circuit cycles”). The module has switched the output off to protect itself. Fix the cause first — check the bulb or LED, its socket and the wiring: if the short circuit is still there, the module switches the output off again.
Which cars
- F-series with front and rear electronic modules (FEM / REM): 1, 2, 3 and 4 Series (F20–F36), M2, M3 and M4 (F87, F80, F82).
- F-series with a body domain controller (BDC): for example the X1 (F48), the 2 Series Active Tourer (F45 / F46) and the F-series MINI.
- G-series with a G11- or G05-type body controller: for example the 5 and 7 Series (G30, G31, G11, G12), the 3 and 4 Series (G20, G21, G22), the X3 (G01) and the X5 (G05) built before mid-2022.
- Not covered: the F10 / F01 generation of the 5 and 7 Series, whose lighting modules have no short-circuit lock to reset (the app says so), and the newest G-series built on the 2021-onward platform, such as the X3 (G45), 5 Series (G60) and 7 Series (G70).
The app recognises the body module from its own answer, not from the model name. Tailgate, rear window and power supply outputs are a separate page, Body Short-Circuit Reset, available on F-series cars with FEM / REM or BDC.
Step by step in the app
- Fix the cause of the short circuit (bulb or LED, socket, wiring).
- Plug the adapter into the OBD port and switch the ignition on. In the app tap Connect, then Open Dashboard.
- Tap Lamp Short-Circuit Reset, then Read Status. A locked output shows “Short circuit — output switched off”.
- Tap Reset next to it, or Reset All Outputs, and confirm. The app reads the output again; “Reset confirmed — the output no longer reports a short circuit.” means the light is free again.
- If a front lamp on an F-series car, or a lamp on a G11-type body controller, has used up its reset allowance, the app offers Reset allowances and then sends the lamp reset again.
- Tailgate or power supply output? Open Body Short-Circuit Reset on the Dashboard, tap Read status, then Reset or Reset all.
Free or premium
| What | Price | Note |
|---|---|---|
| Read lamp and body outputs | Free | See which outputs the module has switched off. |
| Reset lamp outputs | Premium | Lamp Short-Circuit Reset, one output or all of them. |
| Reset body outputs | Premium | Tailgate, rear window and supply drivers — F-series only. |
DiagBimmer is free to download; premium features unlock with a one-time in-app purchase — no subscription. The built-in demo vehicles let you try the paid features before you buy.
Tested on real cars
The lamp status read has been checked on an F30 320i, an F82 M4, a G30 and a G12 730Li. None of these cars had a locked lamp at the time, so a reset of a real locked lamp is not yet in our own test records.
Questions
I cleared the fault codes. Why is the light still dead?
Clearing the fault memory removes the fault entries, but the short-circuit lock is a separate state inside the module. The app reads that state and resets it with its own command.
The light went off again after the reset. What now?
The short circuit is most likely still there. Check the bulb or LED, its socket and the wiring, then reset again.
What if the module refuses every reset?
If the module answers that a channel has reached its maximum number of short circuits, no reset can clear it and the control unit needs replacing. The app tells you when that is the case.
Which adapter do I need?
Any ELM327 v1.5 or newer OBD adapter, or an ENET connection. On iPhone, use a Bluetooth LE or Wi-Fi OBD adapter or a Wi-Fi ENET adapter; Bluetooth Classic and USB adapters work on Android only.
Is it a subscription?
No. Reading the status is free; the resets are part of a one-time premium purchase. You can try the paid features on the built-in demo vehicles first.
Full guide with background and more questions: How to reset the BMW FEM / REM short circuit error (gizliozellikacma.com).